In many of today's processing systems, such as personal computer (PC) systems, there exist ports for connecting various devices. Some of these devices are frequently used by PC users. For example, some devices can connect to system using a Universal Serial Bus (USB) port. Such USB devices may be printers, compact disk read-only-memory (CD-ROM) drives, CD-ROM Writer (CDRW) drives, digital versatile disk (DVD) drives, cameras, pointing devices (e.g., computer mouse), keyboards, joy-sticks, hard-drives, speakers, among other examples. Some of these devices use more of the available USB bandwidth than others. For example, a USB CDRW is a high bandwidth device, while human interface devices (HID), such as computer mice, keyboards and joysticks, are low bandwidth devices.
Different standards of USB technology have different capabilities and support different maximum bandwidths. For example, Universal Serial Bus Specification, revision 1.1, September 1998 (USB 1.1) devices are capable of operating at 12 Mbits/second (Mbps), and Universal Serial Bus Specification, revision 2.0, April 2000 (USB 2.0; also known as high-speed USB) devices are capable of operating at 480 Mbps. More recently, Universal Serial Bus Specification, revision 3.0 was introduced (in August 2008) capable of operating at 5.0 Gbits/second (Gbps) and was updated further in Universal Serial Bus Specification, revision 3.1 in July 2013 to support operation at 10.0 Gbps.